SOURCE: An introduction to Frankenstein; or, the Modern Prometheus, by Mary Wollstonecraft Shelley, in The Essential Frankenstein, edited by Leonard Wolf, Plume, 1993, pp. 296-300.

Shelley's Frankenstein, one of the best-known horror novels of all time, was conceived and begun during the summer of 1816 , during the same sojourn during which Byron wrote the fragment from which Polidori developed The Vampyre. In the following excerpt from her introduction to the 1831 edition of Frankenstein, Shelley outlines the genesis of the two works, dismissing Polidori's initial literary effort. Subsequent scholarship has shown Shelley's account to be largely erroneous.

In the summer of 1816 we visited Switzerland and became the neighbours of Lord Byron. At first we spent our pleasant hours on the lake or wandering on its shores; and Lord Byron, who was writing the third canto of Childe Harold, was the only one among us who put his thoughts upon paper. These...